Insulin action and skeletal muscle blood flow in patients with Type 1 diabetes and microalbuminuria

Our objective was to determine whether Type 1 diabetic patients with microa lbuminura are less sensitive to the effects of insulin on glucose metabolis m and skeletal muscle blood flow, compared to those with normal albumin exc retion, after careful matching for confounding variables. We recruited 10 n ormotensive Type 1 diabetic patients with microalbuminuria and 11 with norm oalbuminuria matched for age, sex, body mass index, duration of diabetes an d HbA(1c). Peripheral and hepatic insulin action was assessed using a two-s tep euglycaemic hyperinsulinaemic clamp (2 h at 0.4 mU kg(-1) min(-1), 2h a t 2.0 mU kg (1) min(-1)) combined with istope dilution methodology. Skeleta l muscle blood flow was determined by venous occlusion plethysmography. Dur ing the clamps, glucose infusion rates required to maintain euglycaemia wer e similar in the microalbuminuric subjects and controls (step 1, 8.2 +/-1.4 (SE) vs 9.2 +/-1.3 mu mol kg (-1) min(-1): step 2, 30.9 +/-2.7 vs 32.0 +/- 3.8 mu mol kg(-1) min(-1)), as was hepatic glucose production basally and a t steady state in step 1. In step 2, hepatic glucose production was lower i n the microalbuminuric group (2.9 +/-0.9 vs 6.4 +/-0.7 mu mol kg(-1) min(-1 ), P=0.005). During step 2, skeletal muscle blood flow increased significan tly above baseline in the normoalbuminuric group (4.1 +/-0.5 vs 3.2 +/-0.4 ml 100-ml(-1) min(-1), P=0.01) but not in the microalbuminuric group (2.4 /-0.3 vs 2.3 +/-0.4 ml 100-ml(-1) min(-1)). In conclusion, microalbuminuria in Type 1 diabetes was found to be associated with impairment of insulin-m ediated skeletal muscle blood flow, but now with insulin resistance. (C) 20 01 Elsevier Science Ireland Ltd. All rights reserved.